Can Spells with long casting times be disrupted by being transformed?

bit of a dense and complex question here. My character was trying to cast leomund’s tiny hut as a ritual, which because it has a long casting time, requires her to maintain concentration. The group was ambushed (though we all passed perception checks so no surprise), and the DM assumed that if he were to polymorph my character, she would lose concentration, and wouldn’t be able to finish the spell because she no longer has a spell list as a CR 0 cat.

I know concentration shouldn’t matter, but is he right about the second part? Could she finish casting the spell as a cat? Does she have to turn back into a kobold first before the spell can resolve? Does anything change if she is casting Glyph of Warding, which isn’t a ritual?

Likewise, in a similar situation, if she later gets true polymorph and turns into a Planatar, while casting raise dead would break concentration as it takes more than 1 action, would she still be able to resolve the casting at the end of 1 hour, if she maintained concentration the whole time?